Drive-in theater speakers severance warning system



2 Sheets-Sheet 1 A WOR/vir B. N. ALSBROOK, JR., EVAL DRIVE-IN THEATER SPEAKERS sEvERANcE WARNING SYSTEM March 19, 1957 Filed Jan.

vMarch 19, 1957 Filed Jan. 2, 1953 B. N. ALsBRooK, JR., ETAL 2,786,098

DRIVE-IN THEATER SPEAKERS SEVERANCE WARNING SYSTEM 2 Sheets-Sheet 2 ATTORNEY United States .Patent Of' *This invention Arelatesto a-warning orzfsignallingsystem4 "adapted rtotrenderboth a visual fand'audible signal 1upon @the Anseverance -`of l the 'cords sof the speakers lin drive-.in

`heaters andthe-like. i

lteisan' object Aof this inventionto provide protective or warning syste'm radapted to `render-both 1avisual --andt aprotective or warning system of Vthis class havingcan-` iidible "wrningmeans, as L4a lbelL- adapted ftxponthe severance of a speaker/to 'rendervranfaudible signal to call attention to theflashing of the.light on the central "panel It is also a further object fthisinveniion topr'vide a warning or signalling system of this class provided with an isolation transformer whereby the full force of the voltage of the system may not be grounded through the body of the person making the severance.

Other and further objects will be apparent when the specification is considered in connection with the drawings in which:

Fig. l is a plan view of a portion of the area of a drive in theater, showing the wiring to the speakers in individual ramps.

Fig. 2 is an electrical diagram showing the wiring of the central panel, and its relation to the wiring of individual ramps or series of ramps.

In drive-in theaters, as shown in Fig. 1, it is conventional to provide a series of pairs 1 of aligned voice magnifying speakers 2 along each ramp or slope-graded portion of the theater. Such speakers, by wiring, not shown, are connected to the vocal recording means which .is co-ordinated with, and actuated by the showing of the film.

Because the speakers are in themselves of value for separate use on other electrical apparatus, theater-goers are often tempted to sever the speaker at their station and drive away with it to appropriate it to such other uses, while more often the severance and appropriation may result from sheer vandalism.

This present invention sets out to avoid such appropriations by warning theater personnel of the severance of a speaker, by the ashing on of a light on a central panel, and by the ringing of a bell to call the attention of such personnel to the signal light. The panel may provide lights to designate a servance at any speaker, or pair of speakers, or fewer lights may be provided so that one light may designate a severance along any one ramp, or bank or pair of ramps.

As shown in Fig. 2, power conductors 3 and 4 are connected to the terminals 5 and 6, respectively, of the 2,786,098 Patented..Mar.t.I9,1957

Tice

f2 primary coil7-ofran isolation transformer.,8. ,'l`he.sec ohdary t 9- of l such .transformer `has the `conductorrline 13 connected ,to its terminal 1\1,and `Ythis line connects Awith the y-line --15- which lextends tof a pair of speakers 1 4inn a..f1rst:ramp bank, .where the line -16 therefrom series- `connects vthe two speakers .2, whilethe line 17 therefrom connects the light 18 in parallel with theconductor 1ine.16.extending,to the `speakers AZ-Wherebythe line 16 --zconstitutesta-low resistanceshunt path `around Athe .light signal.v- -The lines V-16sandu17 -are -then .connected -into 'the line 18', leading toadjacent speaker-stationsin ,the -same ramp, and to speakers, not shown,. in the adjacent ramp, `whentwo such.rampsmayiormaramp bank, and

ffinally tothe llast,pairof..'speakers '1'.adjacentthe panel 5.0.

.At the-tpanelflthe line.,19,from.the last .pair of speakers ..15 has the .lines .21.. and. 22-connected-fthereto `which,parallel-connect a.relay.switch,.includingrthe elec- .tromagnet 23, Ywhich .is normally energized.. as .regards 'the electrical.. circuits ttherethrough, `anda p variable .rev .,sistor .24,..and thenconnect .intothe .line 25, .whchin turn .connectsinto` the .line' 26` which completesthe `circuit by connection .into the. terminal .12 of the secondary coil9 of theisolation transformerS.

`The 4relay unit Vincludes a .double pole switch.27 1ocated adjacentA the normally energized Vcoil 23, .and is` so ,.controlledlbyethe relay ..coil`,-as to .normally be held `openedhut which is .closed when currentis .consumedto nlight. any/-signal -18 by, reason vof `a. break.in..its.shunt..16 ,.andlwhich thereby defenergizes .thelrelay coil. .Closing 30` fthepower conductor 4r3i, the. line .29 totherswitch 27, the

,f fthe :switch .17 ,completes .a circuit` via .thef line .28.lfrom contact l30, theline 3'1` having the light,.32.series.,con nectedtherein, and theline33 to, thepowenconductor 4. "Also upQn theclosing, of "the .switch27. the contact 41 from the terminal 42 to the line 33 complete a circuit parallel connecting the primary coil 38 of the transformer 40 and the light 32.

The bell 45, by means of the lines 43 and 44 therefrom, respectively, to the terminals 47 and 48 of the secondary coil 39, is connected to be rung by the functioning of the transformer 40, when the switch 27 is closed.

It can thus follow that the normally energized relay coil 23 will be de-energized by reason of the resistance to current ow through the light 18 when the severance of the low resistance shunt 16 at any speaker 2 in Ramp Bank A may induce such action, whereupon the circuits through the light 32 and transformer 40 are closed by the operation of the switch 27, whereby the light 32 ashes on to light up the ldesignation of Ramp Bank A, not shown, on the panel 50. At the same time the closing of the switch 27 completes the circuit through the transformer 40 to ring the bell 45 to thereby call attention to the light 32 on the panel 50. Thus the personnel of the theater can be informed of a severance as soon as it takes place, so that they may seek a lighted signal 18 at a speaker station and quickly accost the guilty party before departure can be made from the theater grounds.

At the same time, since it is not desir-able to bodily harm such guilty party, the isolation transformer 8 prevents the full current of the voltage across the power conductors 3 and 4 from being grounded through the body of such guilty party as he severs a speaker.

As shown in Fig. 2, for each additional ramp bank, or ramp, as the case may be, another light 32 must be provided at the panel 50, as well as another normally closed relay 23', resistor 24', and switch 27 It can thus be seen that there has been provided a visual and audible signalling device, operable upon the severance of any speaker, to call attention to such severance and theater parking area.

l designate the relative location of such severance in the It is additionally pointed out that such device, in the form of the isolation transformer, may provide means which will protect even one aspiring to appropriate a speaker from suffering the force of the voltage impact of the power line and thus being shocked, perhaps fatally. This feature is optional, and may be omitted in a case where such danger of shocking an appropriator or would-be appropriator is not to bc considered. In such Vcase the power conductors 3 and 4 connect respectively to fthe conductor lines 13 and 26. p

, Broadly this invention relates to, and provides a signalling device operable to call attention to the location in a drive-in theater, or the like, at which a severance has just been made in an electrical circuit.

What is claimed is: A 1./'A signalling system comprising, a speaker having a connector cord leading thereto and including a current conductor, a signal connected -in parallel with said cord' included conductor, a normally energized relay coil and a variable resistor connected in parallel, and conductor means connecting one side of said parallel connected signal and conductor to one side of said parallel connected coil and resistor, and a pair of power conductors, one connected to the opposite sidel of said parallel connected signal and conductor and one connected to the opposite side of said parallel connected coil and resistor, a second signal and a contact means series connected thereto, said,

connector cord leading thereto and including a current. conductor, a signal connected in parallel with said cord stations.

included connector and arranged so that said. conductor shunts current flow around said signal, a relay coil in series with said parallel connected signal and cord -included conductor, a relay coil actuated switch normally held open by said relay coil so that severance of said speaker cord included conductor closes said switch and a second signal responsive to the closing of said switch.

3. A speaker theft alarm system for a drive-in theater which includes a speaker having a connector cordl leading thereto, -a first electric circuit having a resistance element therein and a low resistance shunt around said element and constituted by acurrent conductor included within said speaker connector cord, a relay having its current ow responsive actuator in said circuit so as to be responsive to change in current ow should said conductor become severed andthereby conne current ow in saidl circuit to flow through said resistance element, a relay controlled circuit and a signal in the relay controlled circuit. l A

4. In aV speaker theft signaling system for a drive-in theater or the like, a series of speaker stations, a signal 'at each station, a relay switch having itsv actuating vcoil rin series circuit with the signals at said stations, an uninterrupted low resistant shunt'around each signal, a

speaker unit to which said shunt extends and whose separation from its station breaks said shunt, whereby the energy consumed by signal operation affects said actuatj'ing coil for relay switch operation, and a separate circuit controlled by the relay switch and containing a general alarm signal at a master station serving all the speaker ReferencesClted in theile of this patent UNITED STATES PATENTS Wetzel et a1. f Ma1-..1, 1949 OTHER REFERENCES I* Telephony, by McMeen and Miller, published by American Tech. Soc., 1922, pages 375-377, 

